particles: in the formulation bottle, sprayer tank mix, spray droplet spectrum and the fate of those droplets. With dissolved or nano-particulate active substances, botanical extracts and fermentation products can be treated functionally as similar to chemical pesticides in this respect, but all biorational pesticides will benefit from careful attention to dose-transfer efficiency. Improved delivery systems are most unlikely to revive a poorly performing BCA, but the performance of a good control agent (as with a chemical pesticide) will be severely reduced by poor delivery systems. FAO provides guidelines on the minimum requirements for agricultural pesticide application equipment (46), but unfortunately in any visit to sprayer stores or farmers in the region, it can be difficult to find equipment that complies with these requirements. For portable equipment (as used by most farmers and especially smallholders), specifications are given for sprayer tanks, pumps, etc., with specific requirements on nozzles. These include: • “The sprayer manufacturer should include in the sprayer manual, information on: nozzle flow Spray quality matters, but it appears increasingly that locally available sprayers are fitted with variable cone nozzles which are impossible to calibrate and produce an infinitely variable range of droplet size spectra and flow rates (47). A relatively small number of large droplets may represent a large proportion of the spray volume (that could have been turned into a large number of more efficient small droplets). These larger droplets are highly likely to run off leaves, fall back onto the ground (‘run-off’ or exo-drift) and be wasted. This can be a contributory factor to poor or variable efficacy. Rice is the primary staple food in the region and therefore a key target crop for development. In the context of the ABC project, experts decided to focus on brown plant hoppers (BPH: often included together with white-backed plant hoppers, Sogatella furcifera), various species of stem borers (Scirpophaga and Chilo spp.) and rice blast (Magnaporthe grisea). However, sheath blight is important in some areas: especially the Vietnamese summer crops, prompting the widespread marketing of validamycin (from the fermentation of Streptomyces hygroscopicus) and a range of other antibiotic-type products. Information on pests and diseases has been based on the considerable amount of literature published by IRRI, which historically made extensive use of cumulative damage data. However, such data did not always reflect the actual variability of damage in an agro-ecosystem and were often 10ISO 10625:2005 specifies system of colour coding for identification of standard hydraulic spray nozzles (e.g. flat fan, deflector and single component cone nozzles) 28 • “Nozzles supplied with or recommended for a sprayer should be manufactured to international standards (ISO)10.” rates, characteristic spray patterns and spray angles … ” 3 Crops: Case studies 3.1 Rice
Implementing Biological Control Agents in the ASEAN Region
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